Hapsburg , (Ger. Habsburg; originally, it is supposed, Habichtsburg or Hawk's Castle), a ruined castle of Switzerland, near Brugg, canton of Aargau, on the Wulpelsberg, on the right bank of the Aar. It was built early in the 11th century, and has given its name to the imperial house of Austria. The first count of Hapsburg was Werner II., a nephew of Werner, bishop of Strasburg, who is represented by genealogists as a descendant of Ethico I., a duke of Alemannia in the 7th century. The descendants of Count Werner augmented the possessions of their house until their acquisitions were divided by the brothers Albert IV. and Rudolph III. in 1232. Rudolph became the founder of the Lauffenburg line, which again separated into the Hapsburg-Lauffenburg and Kyburg branches, of which the former became extinct (in its male line) in 1408, and the latter in 1415. The line of Albert IV., on the other hand, became flourishing through his son Rudolph, who in 1273 was elected emperor of Germany, and, having conquered Ottocar of Bohemia, gave his provinces, Austria, Styria, and Carniola, to his sons Albert, afterward the first German emperor of that name (died in 1308), and Rudolph, on whose death in 1290 his share also reverted to Albert. Under the grandsons of the latter the line again separated into two branches, one of which, numbering among its members the emperor Albert II. (died 1439), became extinct in 1457, with the death of his son Ladislas, king of Hungary, and the other ascended the throne of Germany in the person of Frederick III. (died 1493), whose descendants were now, after the acquisition of the Burgundian dominions, strong enough to make the German imperial dignity stationary and almost hereditary in their house down to the last hour of the German empire (1806). The successors of Frederick III. in that dignity were, of the male line, Maximilian I. (died 1519), Charles V. (abdicated 1556), Ferdinand I. (died 1564), Maximilian II. (1576), Rudolph II. (1612), Matthias (1619), Ferdinand II. (1637), Ferdinand III. (1657), Leopold I. (1705), Joseph I. (1711), and Charles VI. (1740); of the female line (Hapsburg-Lorraine), Francis I. of Lorraine, husband of Maria Theresa, daughter of Charles VI. (1765), Joseph II. (1790), Leopold II. (1792), and Francis II., who, having assumed the title of emperor of Austria in 1804 as Francis L, resigned the German imperial dignity in 1806. His successor in Austria was his son Ferdinand I. (1835-'48), after whose resignation his nephew Francis Joseph, son of the archduke Francis Charles, was declared emperor, Dec. 2, 1848. His son, Rudolph Francis Charles Joseph, born Aug. 21, 1858, is the heir to the crown.

Through Charles V. (I..), who was the son of Philip, son of Maximilian I., and of Juana, daughter of Ferdinand and Isabella, the house of Hapsburg also ascended the throne of Spain, uniting with it the possessions of the house of Burgundy in the Low Countries; while his brother Ferdinand I: succeeded in attaching to the German line the crowns of his brother-in-law Louis II., king of Hungary and Bohemia, after the death of the latter in the battle of Mohacs against the Turks (1526). The Spanish line was continued by Philip II., Philip III., Philip IV., and Charles II., with whom it became extinct in 1700, and was succeeded, after a great struggle involving half of Europe in war, by the Bourbons. The chief Swiss possessions of the house were lost as early as the first quarter of the 14th century, when the Swiss confederation was formed; the rest were ceded to various cantons at later periods, the last as late as 1802. - One of the counts of Hapsburg, Geffery (Gottfried), settled in England in the 13th century, served Henry III. in his wars, and assumed the surname of Feild-ing from the county of Rinfilding (Rheinfelden) in Aargau, then belonging to Germany. He became the progenitor of the Denbigh family, and among the titles of the present earl of Denbigh are those of Viscount and Baron Feilding and count of Hapsburg-Laffenburg and Rheinfelden in Germany. Henry Fielding, the novelist, was a member of this family.